Railway-traffic-controlling apparatus



March 18, 1930. o, GRONDAHL 1,750,801

RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 10, 1927 76 Soul-c0 of Alternating Current I 4 /V (V0012 Tube] lNVE-NTOR A. .O. Grondab/ Patented Mar. 18, 1930 UNITED STATES PATENT OFFICE LABS O. GRONDAHL, F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA RAIIIWAY-TRAFFIO-CON TROLLIN G APPARATUS Application filed September 10, 1927, Serial No. 218,772. Renewed August 29, 1929.

My invention relates to railway traflic controlling apparatus, and particularly to apparatus of the type wherein traffic controllm current is periodically supplied to the tracr rails.

One feature of my invention is the provision of means for periodically supplylng current to the track rail without moving parts.

I will describe one form of'apparatus embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a dlagrammatic view showing one form of apparatus embodying my invention.

Referring to the drawing, the reference characters 10 and 10 desi nate the track rails of a railway along whic traific normally moves in the direction indicated by the arrow, and which rails are divided into sec- 'tions by means of insulated joints 11. I have illustrated my invention as applied to the exit end of only one track section, but it is understood that in actual practice similar apparatus may be applied to each section over an extended stretch of track.

The track rails 10 and 10" are supplied with alternating train governing current from the secondary 2 of a transformer T, the primary 1 of which is constantly supplied with alter- 0 nating currentfrom a source not shown in the drawing. Interposed between the secondary 2 and one of the track rails is a first winding 5 of reactor ilk-having an iron core 4 and a second winding 6. The transformer T is provided with a second secondary 3 which is connected with the input terminals of a rectifier R, and the out ut terminals of the rectier R are connecte with the reactor winding 6 through a neon tube N. The circuit for the reactor winding 6 and neon tube N, which circuit I will term the control circuit for reactor A is ple paths including condensers C, C", respectively. The branch path including condenser C also includes a resistance 8 and a contact 9. The branch path including condensers C and 0 are similarly provided with resistances 8 and 8, and contacts 9 and 9. The condensers C, C and C have so different capacity values. The contacts 9, 9

provided with a plurality of muliand 9 may be controlled in any suitable manner, such for example by traflic conditions in advance, the only essential characteristic being that any one or any group of these contacts may be closed. A variable resistance 7 is preferably included in the control circuit between one of the output terminals of the rectifier R and the point of connection of the first condenser path with this circuit.

The operation of the apparatus is as follows: First assuming that contact 9 is closed, as shown in the drawing, the condenser C will become gradually charged through the resistances 7 and 8 until the voltage across the terminals of this condenser is great enough to render the neon tube N conductive. When the neon tube becomes conductive, current will flow from the rectifier R throu h the control winding 6, and the condenser A will gradually discharge through this winding until the voltage across the condenser drops to such value that the neon tube again becomes non-conducting. This process will be repeated as long as contact 9 remains closed. During the interval in which current is supplied to winding 6, the magnetic core 4 of the reactor A is saturated, so that the reactance of winding 5 is relatively low, with the result that a relatively large amount of current is supplied to the track rails from secondary 2. During the interval in neon tube is non-conductive, no current is supplied to winding 6, and so the reactance of winding 5 is relatively high, and the amount of current supplied to the track rails is relatively small. The frequency at which current is supplied to the control winding 6 will, of course, depend on the capacity value of the condenser C and also on the values of resistances 7 and 8".

When contact 9 is closed and contact 9" is openfithe apparatus will function in the same manner as before, except that the frequency of the current supplied to windin 6 will be different, because of the different capacity value of thecondenser C. When contact 9 is closed, the apparatus will still function as before, except that the frequency of energization of winding 6 will againbo different because of the different capacity I. R. drop across resistance 7 determines the voltage across the neon tube. These'resistances, therefore, taken together with the capacity values of the condensers, may. be used to adjust thefrequency of periodic variation of the current supplied to the track rails by the transformer secondary 2. I

Although as here shown the control winding 6 is used to governthe reactance of winding 5, it is understood that winding 6 may be used in any other suitable manner to periodically vary the amplitude of the current supplied to the rails from secondary 2. For example, winding 6 may be the heating element of a thermo-sensitive relay, the thermo-sensitive element of which is interposed between the secondary 2 and one of the track rails. v

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within theiscope'of the ap-' pended claims without'l'departing from the spirit'and scope of my'inventiom' Having thus described ny-invention, what I claim is a 1. In combination with the rails of a, railway track and a source of alternating ourrent connected therewith, a reactor having two windings one of which is interposedbetween said sourcelandoa track rail, and means including a .neon tub'e, for periodically supplying current to the other winding of said reactor and thereby periodically varying the amplitude of the current supplied to the rails from said source.

2. In combination with the rails of a railway track and a source of alternating current connected therewith, an impedance interposed between said source and a track rail, and-means including a neon tube for periodically varying the value of said impedance and thereby periodically varying the amplitude of the current supplied to the rails from said source. v

3. In combination with the rails of a rail way track and a source of alternating current connected therewith, a circuit including a source of unidirectional current and a winding and a neon tube, a condenser connected across said circuit in multiple with the unidirectional source, whereby said tube periodically becomes conductive to supply current to said winding, and means responsive to the periodic supply of current to said winding for periodically varying the amplitude of the current supplied to the rails from said alternating source.

4. In combination with the rails of a railway track and a source'of alternating current connected therewith, a reactor having two windings the first of which is interposed between said source and a track rail, a circuit including a sourceof unidirectional current and the second winding of said reactor and a neon tube, and a condenser connected acrosssaid circuit in multiple with the unidirectional source whereby said tube periodically becomes conductive to supply current to said second winding and to thereby periodically vary the amplitude of the current sup plied to the rails from said alternating cur rent source.

5. In combination with the rails of a railway track and a source of alternating current connected therewith, a circuit including a source of unidirectional current and a winding and a neon tube, a plurality of condensers having different capacity values, means for selectively connecting said condensers across said circuit in multiple with the source of unidirectional current whereby said tube becomes conductive to supply cur rent to said winding at difierent frequencies depending upon whi h condenser is connected with the circuit, and meansresponsive to the periodic supply of said current to said' winding for periodically varying tude of the current supplied to said alternating source. 1

'6. In combination with the rails of a railway track, a transformer havinga constantlysupplied with alternating current, H

said transformer having a first secondary,

connected with the rails of saidtrack, a second secondary ,on sai ing current to the input circuit of a rectifier, a control circuit supplied,with'unidirectional current by said'rectifier and including a winding and neon tube, a condenser connected across said control circuit in multiple with the rectifier whereby cally becomes conductive to supply current to said winding, and means responsive to the periodic supply 'ofcurrent to said windin for periodically varying the amplitude o the current supplied to the track rails from said firsttransformer secondary.- a 7 In combination with the rails of a railway track and asource of alternatin current connected therewith, a circuit'inc uding a source of unidirectional current and a winding and a neon tube, a condenser and a resistance connected in series across said circuit in multiple with the unidirectional source whereby said tube periodically becomes conductive to supply current to sa d winding,'a resistance interposed between said source and said condenser for controlling the d transformer supply.

the n l the rails 1 said tube p'eriodicharging rate of the condenser, and means responsive to the periodic supply of current to said winding for periodically varying the amplitude of the current supplied to the rails from said alternating current source.

8. In combination with the rails of a railway track and a source of alternating current connected therewith, an im edance interposed between said source and one of the track rails, a winding for varying the value of said impedance, and means including a neon tube for periodicall su plying current to said winding and t ere y periodically varying the amplitude of the current supplied to the rails from said source.

9. In'combination with the rails of a railway track, a source of alternating current connected therewith, a control winding, a neon tube, a condenser, a charging circuit for said condenser including a source of unidirectional current, a discharge circuit for said condenser including said neon tube and said control winding in series and means governed by said control win in for pcriodically varying the amplitude o the current supplied to the rails from said source.

In testimony whereof I aflix my signature.

LABS O. GRONDAHL. 

